A web browser (often referred to simply as a browser, for short) is a software application for accessing web pages on the World Wide Web. Popular web browsers currently include Google Chrome, Mozilla Firefox, Internet Explorer, and Safari, to name a few. Typically, a user will access information on a web page by navigating to a Uniform Resource Locator (URL) associated with the web page, using the web browser. The browser causes data of the web page to be retrieved, which data may then be displayed to the user on his or her computing device. This browser is an example of a user agent—software that acts on behalf of a user.
In particular, where the URL begins with “http:” or “https:” the browser will typically retrieve data of the associated web page in accordance with the Hypertext Transfer Protocol (HTTP). HTTP is an application protocol for exchanging or transferring hypertext—structured text that contains logical links, known as hyperlinks, to text in documents residing on different network nodes. HTTP functions as a request-response protocol in client-server communications: a client (e.g., a web browser) can submit an HTTP request message to a server (e.g., an application executing on a web server that hosts a web page of interest) to request certain resources provided by the server such as a Hypertext Markup Language (HTML) file or other content; the server can then return to the client a response message that may include, for example, the requested content. This content may potentially be displayable on the user's computing device, typically using a rendering engine of the browser. Moreover, while this content typically comprises text, it may, additionally or alternatively, include images and video in such formats as may be supported by the particular browser.